As devices become more universal in the type of functions they support, the range of external media accessories becomes increasingly diverse as well. For example, devices with cellular capabilities may include media players for use with music or video files. In order to take full advantage of the capabilities of such devices, the user typically needs to use more than one accessory device. For example, a cellular telephone device may accommodate a headset with a microphone, but that same headset may not be suitable for music listening. The user may need to switch from headset to ear buds in order to enjoy music on the same device.
Plug connectors (commonly referred to as “plugs”) are typically used to connect computing devices with accessory devices, particularly when audio or video data is involved. FIG. 1A and FIG. 1B illustrate different kinds of conventional plug connectors 100. Plug connectors 100 are generally characterized by a barrel 110 that inserts into a plug receptacle. An insulative body 120 may support the barrels 110 and provide a surface for the user to insert and remove the plug connector. The barrel 110 may include pins 112 or electrical leads that carry signals to and/or from the device to the accessory. In FIG. 1A, the plug 100 corresponds to a 3-pin plug. FIG. 1B shows an alternative 4-pin plug 150. The plug connectors 100, 150 can be inserted into receptacle connectors where the pins of the plug connectors align with corresponding pins (sometimes called “poles”) of the receptacle.
The difference between the 3-pin plug 100 of FIG. 1A and the 4-pin plug 150 of FIG. 1B is the presence of an extra pin 122 at the base of the 4-pin plug (FIG. 1B). When a comparison is made between the plug connectors of FIG. 1A and FIG. 1B, the pins 1, 2, and 3 are relatively aligned, but pin 4 on plug B “overlaps” pin 3 on plug A.
In addition to pin configuration, the plug connectors of FIG. 1A and FIG. 1B may be of different dimensions. The dimension of a plug connector is often is a measurement of girth of the barrel 110. For example, in FIG. 1A the plug connector 100 includes a 2.5 mm barrel 110, and in FIG. 1B, the plug connector 150 includes is a 3.5 mm barrel 160. For dimensions are fairly standard in existing plug connectors.
FIG. 2 shows some common conventions for signal connection to connectors. Some accessories also include an “answer” button on the microphone signal and/or selector switch to distinguish between a headset and a headphone operation.
An inherent difficulty in supporting the different kinds of plug accessories with one device is connector compatibility. For example, media plugs that connect certain accessories to mobile computing devices differ in physical dimensions, number of contacts (or “pins”), and electrical signal connectivity. Adapters exist for mating plug connectors of one pin configuration and/or dimension into a receptacle for another kind of plug connector or pin configuration. However, such adapters often do not fully support the connected plug connector. For example, many times, a 3-pin plug can plug into a 4-pole jack using an adapter. However, the extra pin will be shorted to pin 3, causing the accessory to operate improperly.
Mobile computing devices in the form of smart phones and wireless messaging devices often have the most use for plug connectors. Accessories for such devices often have many added functions. For example, headsets with microphones often have an “answer” button that can be actuated to communicate a signal on one of the signal lines to enable an incoming call to be picked up.
FIG. 3A to FIG. 3C illustrate examples of existing plug connectors and pin configurations commonly in use today. FIG. 3A illustrates a 3-pin plug connector 310 configured for a headset accessory. The headset accessory may correspond to a device that supports audio output and microphone capabilities. To accommodate the headset accessory, there is a first pin 312 for a microphone, a second pin 314 for an earbud, and a third pin 316 for ground. The pin configuration enables the headset accessory to be supported with monotone audio and microphone capabilities.
FIG. 3B illustrates another 3-pin connector plug 320 configured for a headphone accessory. The headphone accessory may correspond to a device that supports audio, preferably in stereo. The pin configuration provided includes (i) a first pin 322 for a left audio channel, (ii) a second pin 324 for a right channel audio, (iii) a third pin 326 for ground.
FIG. 3C illustrates a 4-pin connector plug 330, configured as a combination headphone/headset accessory device. The pin configuration includes (i) a first pin 332 for a left audio channel, (ii) a second pin 334 for a right audio channel, (iii) a third pin 336 for a microphone, and (iv) a fourth pin 338 for ground. Typically, the 4-pin connector plug 330 uses the thicker 3.5 mm barrel.
A standard and commonly-available adapter exists for adapting from 3.5 mm to 2.5 mm. FIG. 3D is a diagram that shows the use of such an adapter 380. The adapter does not distinguish between what kind of signals are to be carried (e.g. stereo headphones, powered noise-canceling headphones or amplified multimedia speakers). As such, adapters 380 do not generally enable full support of all adapted accessory devices. Moreover, adapters that convert pin count (e.g. 4-pin to 3-pin) are not commonly available.